Fuel-injection system

ABSTRACT

A fuel-injection system for the injection of fuel into an internal combustion engine includes at least one fuel injector and a fuel-distributor line as well as for each fuel injector a corrugated-tube bellows, which is able to be connected to an inflow section of the fuel injector. Deformation-energy absorbing elastomeric material abuts with an initial stress against at least some sections of the corrugated-tube bellows.

FIELD OF THE INVENTION

The present invention relates to a fuel-injection system for injectingfuel into an internal combustion engine.

BACKGROUND INFORMATION

German Published Patent Application No. 28 29 057 describes afuel-injection system which supplies fuel to a mixture-compressinginternal combustion engine having external ignition as a function ofoperating parameters. The fuel-injection system encompasses a metalfuel-distributor line, which, via at least one branch line, is connectedto at least one fuel injector, the branch line being embodied as a metaltube and connected to the fuel injector by manner of a threadedconnection. Easily bendable metal is used as material for the branchline. Arranged between the threaded connection on the branch line andthe fuel injector are thin-walled metal bellows in the form of acorrugated-tube bellows by which a lateral offset between the beginningof the branch line on the fuel-distributor line and the fitting positionof the fuel injector is compensated; in addition, the operating noisesemanating from the fuel injector are damped by the yielding of thebellows.

German Published Patent Application No. 28 29 057 describes afuel-injection system such that while the flexurally soft bellows havingthin material thickness does reduce a transmission of solid-borne noiseto the fuel-distributor line, it is excited to oscillations itself andradiates noise. The natural resonance characteristic of thecorrugated-tube bellows may be influenced only to a negligible degree.The corrugated-tube bellows, if it is made of an elastic sheet metal,has only low self-damping.

Finally, due to the vibrations of the internal combustion engine duringoperation, the corrugated-tube bellows are in danger of breaking orripping if insufficient self-damping occurs. In the case of directlyinjecting fuel injectors and at the high pressures required in thiscontext, the connection between a fuel injector and the fuel-distributorline is safety-relevant and must not break under any circumstances.

U.S. Pat. No. 2,014,355 describes a pipe connection in the form of acorrugated tube by which the transmission of vibrations is meant to beprevented or reduced. On the outside, the corrugated tube is surroundedby an envelope that does not touch the corrugated tube and is rigidlyconnected to one pipe section at one end. At its other end, the envelopeis sealed from the other pipe section by a flexible seal, the envelopeshielding from noise originating in the corrugated tube.

Other systems provide that the natural oscillation characteristic of thecorrugated tube may not be influenced. The oscillation characteristic ismerely influenced indirectly with respect to one another, via thestiffness of the two pipe sections, since these tube sections are dampedin their relative movements via the sleeve and the seal. Moreover, theconfiguration consists of several parts and is complicated.

SUMMARY OF THE INVENTION

The fuel-injection system according to the present invention may providethat the natural resonance characteristic and the noise damping of thecorrugated-tube bellows may be influenced to a wide extent. Also, thedamping corrugated-tube bellows according to the present invention maybe manufactured and adapted in its damping values in an uncomplicatedand cost-effective manner. In addition, the tightness of thefuel-conveying components does not depend on the deformability of aseal, such as an O-ring seal. The safety, as it relates to a componentmalfunction during the service life, is increased.

Elastomeric rings are arranged, radially on the outside, in the innerfolds of the corrugated-tube bellows.

This exemplary embodiment may be manufactured with O-rings, for example,and is able to be produced in a cost-effective manner. The inner foldsare zones of great deformation during longitudinal oscillations of thecorrugated-tube bellows. Elastomeric rings abutting there dampen theseoscillations.

Alternatively, or in addition, an elastomeric hose may abut against thecorrugated-tube bellows radially on the outside, this hose abuttingsolely against outer folds of the corrugated-tube bellows.

Only one additional component is mounted in the production. Since allouter folds are joined to each other in the longitudinal direction in amanner that provides damping, the damping is especially high.

Using a union nut, which presses a sealing cone radially against acylinder section of the corrugated-tube bellows, the corrugated-tubebellows may be joined to the inflow section in a releasable manner.

As an alternative, the union nut sealingly presses a single fold of thecorrugated-tube bellows against the inflow section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a section through an exemplary embodiment of afuel-injection system configured according to the present invention, inthe sectional plane of a fuel injector and a corrugated-tube bellows ofa fuel-distributor line.

FIG. 2 shows an exemplary embodiment of a corrugated-tube bellows and aninflow section of a fuel injector in a sectioned view.

FIG. 3 shows an additional exemplary embodiment of a corrugated-tubebellows and an inflow section of a fuel injector in a sectioned view.

DETAILED DESCRIPTION

FIG. 1 shows a section through an exemplary embodiment of afuel-injection system 1 according to the present invention in thesectional plane of a fuel injector 2 and a corrugated-tube bellows 3 ofa fuel-distributor line 4. Fuel injector 2 is shown only in the regionof an inflow section 5, which is provided with a thread 6 for a unionnut 7. When tightened, union nut 7 presses on an upper conical surface 8of a sealing cone 9, which is moved into inflow section 5 by manner of alower conical surface 10, thereby radially compressing sealing cone 9and pressing it against a cylinder section 11 of corrugated-tube bellows3. Due to the high surface pressure acting on lower conical surface 10and on cylinder section 11, a fuel inflow 12 is sealed, without anelastomer coming into contact with the fuel.

At its other end, corrugated-tube bellows 3 is sealingly joined tofuel-distributor line 4 by a welded seam 13.

Inserted in inner folds 14 of corrugated-tube bellows 3, with an initialstress, are elastomeric rings 15, these elastomeric rings lying at theoutside of corrugated-tube bellows 3, in the rounded grooves formed byinner folds 14, and are not in contact with the fuel.

If corrugated-tube bellows 3 is incited to expansions and contractions,especially in its longitudinal axis, by the vibrations occurring duringoperation of an internal combustion engine, elastomeric rings 15 absorbenergy and damp this movement. The noise characteristic and the naturaloscillation characteristic of corrugated-tube bellows 3 are thusinfluenced in an effective manner. This damping may be effected in acost-effective manner. Above all, an adaptation is easily accomplishedby using elastomeric rings 15 that have a different modulus ofelasticity and/or by using a different number of elastomeric rings 15.For instance, only every second inner fold 14 may be provided with anelastomeric ring 15 in order to reduce the damping of corrugated-tubebellows 3.

FIG. 2 shows a section through an exemplary embodiment of afuel-injection system 1 configured according to the present invention.The exemplary embodiment deviates from the configuration in FIG. 1 onlyin the region of an inflow section 16 to fuel injector 2, and withrespect to a union nut 17.

Identical components bear matching reference numerals. Shown is thesectional plane of fuel injector 2 and corrugated-tube bellows 3 as wellas of fuel-distributor line 4.

Formed on inflow section 16 is thread 6 for union nut 17.Corrugated-tube bellows 3 is held in this position in that a flange 18of union nut 17 presses an edge 19 against inflow section 16.

Fuel inflow 12 is sealed by the surface pressure of the edge in asealing line 20 with respect to inflow section 16, without an elastomercoming into contact with the fuel.

At its other end, corrugated-tube bellows 3 is sealingly connected tofuel-distributor line 4 by a welded seam 13. Inserted with an initialstress in inner folds 14 of corrugated-tube bellows 3 are elastomericrings 15.

This configuration effects a sealing and a releasable affixation ofcorrugated-tube bellows 3 on inflow section 16 of fuel injector 2 in aneffective manner.

FIG. 3 shows another exemplary embodiment of the present invention. Theconfiguration corresponds to that of FIG. 2, with the only differencethat no elastomeric rings 15 are present, but a elastomeric hose 22 isused instead. Corrugated-tube bellows 3 and inflow section 16 of fuelinjector 2 as well as fuel-distributor line 4 are shown in a sectionalview. Union nut 17, which engages with thread 6 at inflow section 16,retains edge 19 of corrugated-tube bellows 3 at inflow section 16 bymanner of flange 18.

At its other end, corrugated-tube bellows 3 is sealingly connected tofuel-distributor line 4 by a welded seam 13.

Elastomeric hose 22 is drawn over corrugated-tube bellows 3, for exampleby shrink-fitting a shrink tube. In an effective manner, elastomerichose 22 also damps the relative movements of adjacent outer folds 21. Indoing so, elastomeric hose 22 in each case abuts against corrugated-tubebellows 3 only in the region of outer folds 21.

Noise damping may thus be achieved in a cost-effective configuration.

It is also possible to provide elastomeric rings, as shown in FIGS. 1and 2, in addition to elastomeric hose 22.

1. A fuel-injection system for injecting fuel into an internalcombustion engine, comprising: at least one fuel injector, afuel-distributor line which includes, for each of the at least one fuelinjector, a corrugated-tube bellows able to be connected to an inflowsection of the at least one fuel injector; and deformation-absorbingelastomeric material which abuts with an initial stress against thecorrugated-tube bellows at least in some sections; wherein: theelastomeric material is in the form of a combination of an elastomerichose that abuts against the corrugated-tube bellows radially on anoutside of the corrugated-tube bellows, and a plurality of elastomericrings arranged in inner folds of the corrugated-tube bellows radially onthe outside of the corrugated-tube bellows.
 2. The fuel-injection systemof claim 1, wherein the elastomeric material is in a form of a pluralityof elastomeric rings arranged in inner folds of the corrugated-tubebellows radially on an outside of the corrugated-tube bellows.
 3. Thefuel injection system of claim 1, wherein the elastomeric material is ina form of an elastomeric hose that abuts against the corrugated-tubebellows radially on an outside of the corrugated-tube bellows.
 4. Thefuel-injection system of claim 3, wherein the elastomeric hose abutsonly against only outer folds of the corrugated-tube bellows.
 5. Thefuel-injection system of claim 3, wherein the corrugated-tube bellows isjoined to the inflow section in a releasable manner via a union nut. 6.The fuel-injection system of claim 5, wherein the union nut isconfigured to press a sealing cone radially against a cylinder sectionof the corrugated-tube bellows.
 7. The fuel-injection system of claim 5,wherein the union nut is configured to sealingly press an edge of thecorrugated-tube bellows against the inflow section.
 8. Thefuel-injection system of claim 7, wherein the edge is one of a pluralityof folds of the corrugated-tube bellows.
 9. The fuel-injection system ofclaim 5, wherein the inflow section includes a thread for the union nut.10. The fuel-injection system of claim 6, wherein: the sealing coneincludes a first conical surface and a second conical surface; the unionnut is configured to press on the first conical surface; and the sealingcone is configured to move into the inflow section via the secondconical surface when the union nut presses on the first conical surface.11. The fuel-injection system of claim 2, wherein the elastomeric ringsare arranged in every second inner fold of the corrugated-tube bellows.12. The fuel-injection system of claim 2, wherein the corrugated-tubebellows is joined to the inflow section in a releasable manner via aunion nut.
 13. The fuel-injection system of claim 12, wherein the unionnut is configured to sealingly press an edge of the corrugated-tubebellows against the inflow section.
 14. The fuel-injection system ofclaim 12, wherein the union nut is configured to press a sealing coneradially against a cylinder section of the corrugated-tube bellows. 15.The fuel-injection system of claim 14, wherein: the sealing coneincludes a first conical surface and a second conical surface; the unionnut is configured to press on the first conical surface; and the sealingcone is configured to move into the inflow section via the secondconical surface when the union nut presses on the first conical surface.16. The fuel-injection system of claim 12, wherein the inflow sectionincludes a thread for the union nut.
 17. The fuel-injection system ofclaim 1, wherein the corrugated-tube bellows is joined to the inflowsection in a releasable manner via a union nut.
 18. The fuel-injectionsystem of claim 17, wherein the union nut is configured to press asealing cone radially against a cylinder section of the corrugated-tubebellows.
 19. The fuel-injection system of claim 17, wherein the unionnut is configured to sealingly press an edge of the corrugated-tubebellows against the inflow section.